The primary purpose of this study is to examine the respiratory cancer mortality experience of workers in the chemical industry who have been exposed to chloromethyl methyl ether (CMME). This will be accomplished by updating the mortality experience for the period 1973-1977 among workers in the six firms previously included in our epidemiologic study of occupational exposure to CMME. In addition, all exposed and nonexposed production workers in a seventh firm (plant on the West Coast) will be included in our retrospective cohort for complete mortality followup from the year in which CMME operations first began, 1955, through the end of 1977. Respiratory cancer and other mortality experience of the CMME-exposed workers will be characterized according to duration and intensity of CMME exposure; the temporal patterns of respiratory cancer mortality, including estimation of the induction-latency period, will also be examined. Ascertainment of deaths among separated employees will be based on the searching service of the Social Security Administration. Those not indicated as dead by the Social Security Administration will be traced further for vital status ascertainment by utilization of other resources including the Internal Revenue Service, Post Offices, State Motor Vehicle Bureaus and Union records. Death certificates will be located and obtained, and diagnostic confirmations will be gotten from appropriate physicians, autopsy records, and/or hospitals when any form of cancer is listed as a cause.